I would actually say that coding style is a big predictor of how likely an interview candidate would turn out to be a good developer in a team. Casing isn't irrelevant at all, it's a predictor. It has nothing to do with piousness. Another indicator of bad java developers (in my experience) is those that write near 'c', lots of for(int i=0; i<.... and not using language constructs that are their to reduce bugs. Another good indicator I have found (in java) is little to no use of 'final'.
If you'd have prefaced your coding in the interview with "I'm not familiar with Java, I use X, but I'll take a stab at the problem" I'm sure the interviewer would have been less worried about your style, but if you claim to know a language, you'll know the conventions too.